1. Field of the Invention
The present invention relates generally to apparatus and methods for converting parameter indications to light and color indications, and, more particularly, to apparatus and methods for transforming temperature sensor readings into colors and displaying the colors.
2. Background
In many systems a need exists for observing and monitoring temperatures. For example, internal combustion engines are often equipped with temperature gauges. The gauges indicate to the operator of the engine the temperature of the coolant or lubricant of the engine. For a driver of a car, monitoring of the temperature is of secondary importance in comparison to other tasks that the driver needs to perform at the same time. The driver has to drive the car first; monitoring of the gauges comes second. This statement plainly applies to boat operators, pilots, and construction equipment operators. It is therefore important in many applications to provide an easily readable temperature gauge, to allow the person monitoring the temperature to comprehend the gauge's indication after just a quick glance at the gauge.
In other applications, the temperature display is provided to children or other consumers without a technical understanding of the effect of temperature on the operation, safety, or reliability of the device that is being monitored. A mere red zone marking on the face of a dial is not always adequate to inform the consumer of the undesirable consequences flowing from temperatures that are too high or too low. In addition, finer temperature range gradations may be necessary or desirable for proper operation of the monitored device. The display of temperature in these applications should be tailored to the less sophisticated consumers, and it should impart an intuitive understanding of the meaning of the different temperature zones and the consequences that can result from continued operation in these temperature zones. A simple dial gauge, analog or digital, may not suffice in these applications.
A number of devices in existence change color with temperature in a controllable maner. Strips of material or tubes filled with liquids that change color after exposure to a temperature above a preset limit are available. Similarly, materials that change color after exposure to a preset time-temperature integral are also used, for example, for quality control of foods and of biological specimen. Generally, articles made from these materials suffer from one or more of the following disadvantages. First, they are of a slow-reacting variety and do not display temperature changes in real time. Second, they depend upon direct contact with the article whose temperature is being measured; remote observation of such temperature sensors is impractical. Third, the devices change color only within a predetermined range of temperatures, and the range cannot be easily moved up or down the temperature scale, expanded, contracted, or otherwise varied. Fourth, the color spectrum of such devices is limited. Typically, only one or two colors are available. Fifth, these articles are usually passive devices that do not emit light; therefore, they are more difficult to see, especially in the dark, and do not adequately solve the readability problem. Finally, the color change in many such articles is irreversible: they are single-use, disposable temperature indicators.
A need thus exists for devices that allow a person to read a temperature at a glance. Another need exists for easily readable temperature gauges that display real-time temperatures. Still another need exists for easily readable temperature gauges that can be physically separate and remote from the object whose temperature they display. A further need exists for temperature display devices that can be configured to display different temperature ranges with high visibility, in multiple colors, and that overcome the shortcomings of existing technologies.